The following relates to optical devices. It finds particular application in conjunction with the mounting or packaging of high-power light emitting diode chips, and will be described with particular reference thereto. The following finds more general application in conjunction with mounting or packaging of light emitting chips generally, such as mounting or packaging light emitting diode chips generally, light emitting semiconductor laser chips, non-semiconductor-based light emitting chips such as organic-based light emitting diode chips, and so forth.
Semiconductor chips are routinely mounted or packaged by securing the chip to a support surface of printed circuit board, sub-mount, or other support that provides structural support and thermal heat sinking. In a common approach, the chip includes electrodes disposed on a side of the chip to be bonded to the support, and electrically conductive bonding bumps are formed either on the chip or on the support. The chip is then bonded to the bonding bumps, simultaneously providing mechanical securing of the chip to the support and electrical connection of the electrodes of the chip to printed circuitry or other electrically conductive paths on or in the support.
In securing a semiconductor chip to a support, it is known to dispose an underfill material of epoxy, resin, or another formable material between the chip and the support. Such an underfill material can be applied before the chip is secured to the support, or after it is secured by injecting the underfill material into the gaps between the secured chip and the support. The underfill material provides enhanced mechanical support, provides elasticity to accommodate mechanical strain introduced by differential thermal expansion, and enhances thermal contact between the chip and the support.
The following discloses improved underfill techniques for light emitting chips, and light emitting devices incorporating same.